Implementation of a two-dimensional array sorted by a row or column in Python

This article mainly describes the Python implementation of a two-dimensional array in accordance with a row or column of the method, combined with a specific example of Python using the Lexsort method of the NumPy module for two-dimensional array to sort the common operation skills, the need for friends can refer to the next

This example describes how Python implements a two-dimensional array to sort by a row or column. Share to everyone for your reference, as follows:

Lexsort supports the ordering of arrays in the order of specified rows or columns; is an indirect sort, lexsort does not modify the original array and returns the index.

(corresponding to the Lexsort one-dimensional array is argsort a.argsort() so used, Argsort also does not modify the original array, return index)

By default, the last line element has a small to large sort, which returns the position of the last row of elements after the index is sorted.

Sets the array A, the returned index Ind,ind returns a one-dimensional array

For a one-dimensional array, A[ind] is the sorted array.

For a two-dimensional array, an example is detailed below.

Import NumPy as Np>>> aarray ([[2, 7, 4, 2],    [+, 9, 1, 5],    [22, 12, 3, 2]])

Sort by the last column order

>>> A[np.lexsort (A.T)]array ([[3, 2],    [2, 7, 4, 2],    [35, 9, 1, 5]])

Sort by the last column in reverse order

>>>a[np.lexsort (-A.T)]array ([[[7], 9, 1, 5],    [2, 4, 2, 22],    [, 12, 3, 2]])

Sort by first column order

>>> A[np.lexsort (A[:,::-1]. T)]array ([[2, 7, 4, 2],    [+, 3, 2],    [35, 9, 1, 5]])

Sort by last line order

>>> A.t[np.lexsort (a)]. Tarray ([[2, 4, 7, 2], [5, 1, 9, +    ],    [2, 3, 12, 22]])

Sort by first row order

>>> A.t[np.lexsort (a[::-1,:])]. Tarray ([[2, 2, 4, 7],    [5, +, 1, 9],    [2, 22, 3, 12]])